Optoelectronic systems are increasing in their application to electronic equipment. High performance computers and computer network components increasingly involve conversion of computer data signals to photonic signals for transmission from one device to another, while such photonic signals require conversion to electronic data signals for use in the recipient electronic device.
Coupling optoelectronic components to waveguides remains an awkward aspect of manufacturing optoelectronic systems. Optoelectronic components are manufactured as small as possible, and therefore coupling requires precision alignment of components to waveguides. At the same time, waveguides such as optical fibers are very fragile and require secure encapsulation for mechanical stability and endurance. It is also difficult to achieve such requirements while keeping the resulting volume of a coupling as small as possible, a parameter that can be very important, if not essential, in many applications.
The encapsulation of microelectronic chips is very well known in the art and is commonly used to protect microchips in all varieties of chip packages. The method commonly used is to use a plastic resin and drop a glob of the resin over the wirebonded microchip within its package. U.S. Pat. No. 4,819,041 granted Apr. 4, 1989 and U.S. Pat. No. 5,313,365 granted May 17, 1994 both are good examples of methods used to encapsulate microchips within specific packages. These methods use types of plastic resins to fill a cavity where the microchip has been placed with (typically) opaque resin and without any consideration for the surface profile of the resin. Other examples in the prior art describe transparent epoxies such as U.S. Pat. No. 6,075,911 granted Jun. 13, 2000 and U.S. Pat. No. 6,269,209 granted Jul. 31, 2001 are examples of transparent epoxy or silicon are used with optoelectronic device and optical fibers. These patents describe how the two elements are aligned and then subsequent to the alignment how the epoxy or silicon is injected between the optoelectronic device and the optical fiber to increase coupling and provide protection.
There are several prior-art references that are still patent pending that describe encapsulation of optoelectronics. U.S. patent application Pub. No. US 2002/0001869 dated Jan. 3, 2002 describes an encapsulation technique that uses a sacrificial layer over the encapsulated optoelectronic and includes methods for placing lenses over the open window, but does not describe a polishing method to reduce the thickness of the encapsulation, nor is alignment an issue. U.S. patent application Pub. No. US 2002/0020803 dated Feb. 21, 2002 describes a method of encapsulating an entire photodetector and support electronics in an over-molded type transparent resin that includes an embedded lens that allows for light to pass through the resin to the optoelectronic device. This prior-art also does not allow for 2-D alignment and does not include polishing to create the window. Finally, U.S. patent application Pub. No. US 2002/0181899 dated Dec. 5, 2002 discusses a method for imprinting a flat, but angled surface, on a transparent epoxy resin that encapsulated an optoelectronic device. The alignment method requires dowel pin alignment and is not amenable to polishing or 2-D alignment.